class Solution {
public:
    int climbStairs(int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (n <= 1) {
            return 1;
        }
        vector<int> dp(n + 1);
        dp[0] = 1;
        dp[1] = 1;

        for (int i = 2; i <= n; ++i) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        return dp[n];
    }
};
